The first prospective study of TVUS and CA 125 with survival as the primary outcome was completed in 2009. Of the 3,532 high-risk women screened, 981 were BRCA mutation carriers, of which 49 developed ovarian cancer. The 5- and 10-year survival was 58.6% (95% CI, 50.9-66.3) and 36% (95% CI, 27-45), respectively, and there was no difference in survival between carriers and noncarriers. A major limitation of the study was the absence of a control group. Despite limitations, this study suggests that annual surveillance by TVUS and CA 125 level appear to be ineffective in detecting tumors at an early stage to substantially influence survival.
Level of evidence: 4
Serum CA 125
Serum CA 125 screening for ovarian cancer in high-risk women has been evaluated in combination with TVUS in a number of retrospective studies, as described in the previous section.[7,116,117,118,119,120,121,122,123,124,125]
The National Institutes of Health (NIH) Consensus Statement on Ovarian Cancer recommended against routine screening of the general population for ovarian cancer with serum CA 125. (Refer to the Combined Screening With CA 125 and TVU section of the Ovarian Cancer Screening summary for more information.) The NIH Consensus Statement did, however, recommend that women at inherited risk of ovarian cancer undergo TVUS and serum CA 125 screening every 6 to 12 months, beginning at age 35 years. The Cancer Genetics Studies Consortium task force has recommended that female carriers of a deleterious BRCA1 mutation undergo annual or semiannual screening using TVUS and serum CA 125 levels, beginning at age 25 to 35 years. Both recommendations are based solely on expert opinion and best clinical judgment.
Level of evidence: 5
Other candidate ovarian cancer biomarkers
The need for effective ovarian cancer screening is particularly important for women carrying mutations in BRCA1 and BRCA2, and the mismatch repair genes (e.g., MLH1, MSH2, MSH6, PMS2), disorders in which the risk of ovarian cancer is high. There is a special sense of urgency for BRCA1 mutation carriers, in whom cumulative lifetime risks of ovarian cancer may exceed 40%.
Thus, it is expected that many new ovarian cancer biomarkers (either singly or in combination) will be proposed as ovarian cancer screening strategies during the next 5 to 10 years. While this is an active area of research with a number of promising new biomarkers in early development, it is important to acknowledge that, at present, none of these biomarkers alone or in combination have been sufficiently well studied to justify their routine clinical use for screening purposes, either in the general population or in women at increased genetic risk.
Before addressing information related to emerging ovarian cancer biomarkers, it is important to consider the several steps that are required to develop and, more importantly, validate a new biomarker. One useful framework is that published by NCI Early Detection Research Network investigators. They indicated that the goal of a cancer-screening program is to detect tumors at an early stage so that treatment is likely to be successful. The gold standard by which such programs are judged is whether the death rate from the cancer for which screening is performed is reduced among those being screened. In addition, the screening test must be sufficiently noninvasive and inexpensive to allow widespread use in the population to be screened. Maintaining high test specificity (i.e., few false-positive results) is essential for a population screening test, because even a low false-positive rate results in many people having to undergo unnecessary and costly diagnostic procedures and psychological stress. It is likely that the use of several such cancer biomarkers in combination will be required for a screening test to be both sensitive and specific.